Position detection apparatus, machine tool apparatus, and exposure apparatus

Patent metadata

Field	Value
Publication number	US-10209102-B2
Application number	US-201715453232-A
Country	US
Kind code	B2
Filing date	Mar 8, 2017
Priority date	Mar 14, 2016
Publication date	Feb 19, 2019
Grant date	Feb 19, 2019

Abstract

A position detection apparatus (100) includes a scale (20) including a reference position grating (22), a detector (10), a detection grating (19), and a signal processor (10), the signal processor acquires a relative reference position between the scale and the detector by using a light intensity distribution of a divergent light beam obtained via the reference position grating and the detection grating, the detection grating has a first spatial frequency that is offset by a predetermined frequency offset amount with respect to a local spatial frequency of an interference image from the reference position grating, the detection grating is provided in an optical path between the scale and a light receiver of the detector, and the light receiver detects a component of a second spatial frequency that is lower than the first spatial frequency in the light intensity distribution transmitting through the detection grating.

First claim

What is claimed is:

1. A position detection apparatus comprising:
a scale including a reference position grating configured to change a pattern period along a first direction;
a detector including a light source configured to emit a divergent light beam, a detection grating configured to change a pattern period in the first direction, and a light receiver including a plurality of light receiving elements arrayed along the first direction; and
a signal processor configured to process a signal output from the detector, wherein:
the scale and the detector are relatively movable in the first direction,
the signal processor acquires a relative reference position between the scale and the detector by using a light intensity distribution of the divergent light beam obtained via the reference position grating and the detection grating,
the detection grating has a first spatial frequency that is offset by a predetermined frequency offset amount with respect to a local spatial frequency of an interference image from the reference position grating,
the detection grating is provided in an optical path between the scale and the light receiver, and
the light receiver detects a component of a second spatial frequency that is lower than the first spatial frequency in the light intensity distribution transmitting through the detection grating.

2. The position detection apparatus according to claim 1 , wherein the light receiver includes a plurality of light receiving element groups that are cyclically arrayed to detect a plurality of phase components of the second spatial frequency.

3. The position detection apparatus according to claim 1 , wherein the predetermined frequency offset amount is constant in the detection grating.

4. The position detection apparatus according to claim 1 , wherein a spatial frequency of the reference position grating linearly changes in the first direction.

5. The position detection apparatus according to claim 1 , wherein a spatial frequency of the reference position grating nonlinearly changes in the first direction.

6. The position detection apparatus according to claim 5 , wherein the spatial frequency of the reference position grating quadratically changes in the first direction.

7. The position detection apparatus according to claim 1 ,
wherein the detection grating includes transmission parts and light shielding parts with unequal intervals that are alternately arrayed along the first direction, and
wherein the transmission parts of the detection grating include a light scattering structure in the first direction.

8. The position detection apparatus according to claim 7 , wherein the light scattering structure includes a spatial frequency that is higher than the first spatial frequency.

9. The position detection apparatus according to claim 1 , wherein the signal processor is configured to:
calculate a first phase signal and a second phase signal that have different phases by 90 degrees from each other based on the signal output from the detector, and
calculate, as a first evaluation value, a square root of a sum of a square of the first phase signal and a square of the second phase signal to compare the first evaluation value with a predetermined threshold value to acquire the reference position.

10. The position detection apparatus according to claim 1 , wherein the signal processor is configured to:
calculate a first phase signal and a second phase signal that have different phases by 90 degrees from each other based on the signal output from the detector,
calculate, as a first evaluation value, a square root of a sum of a square of the first phase signal and a square of the second phase signal,
calculate, as a second evaluation value, a phase angle obtained by an arctangent operation of the first phase signal and the second phase signal, and
acquire the reference position based on the first evaluation value and the second evaluation value.

11. A machine tool apparatus comprising:
a machine tool including at least one of a robot arm and a conveyer configured to convey an object to be assembled, and
a position detection apparatus configured to detect at least one of a position and an attitude of the machine tool,
wherein the position detection apparatus comprises:
a scale including a reference position grating configured to change a pattern period along a first direction;
a detector including a light source configured to emit a divergent light beam, a detection grating configured to change a pattern period in the first direction, and a light receiver including a plurality of light receiving elements arrayed along the first direction; and
a signal processor configured to process a signal output from the detector, wherein:
the scale and the detector are relatively movable in the first direction,
the signal processor acquires a relative reference position between the scale and the detector by using a light intensity distribution of the divergent light beam obtained via the reference position grating and the detection grating,
the detection grating has a first spatial frequency that is offset by a predetermined frequency offset amount with respect to a local spatial frequency of an interference image from the reference position grating,
the detection grating is provided in an optical path between the scale and the light receiver, and
the light receiver detects a component of a second spatial frequency that is lower than the first spatial frequency in the light intensity distribution transmitting through the detection grating.

12. An exposure apparatus comprising:
a stage configured to mount a semiconductor wafer to be movable in a two-dimensional direction; and
a position detection apparatus configured to detect a position of the stage,
wherein the position detection apparatus comprises:
a scale including a reference position grating configured to change a pattern period along a first direction;
a detector including a light source configured to emit a divergent light beam, a detection grating configured to change a pattern period in the first direction, and a light receiver including a plurality of light receiving elements arrayed along the first direction; and
a signal processor configured to process a signal output from the detector, wherein:
the scale and the detector are relatively movable in the first direction,
the signal processor acquires a relative reference position between the scale and the detector by using a light intensity distribution of the divergent light beam obtained via the reference position grating and the detection grating,
the detection grating has a first spatial frequency that is offset by a predetermined frequency offset amount with respect to a local spatial frequency of an interference image from the reference position grating,
the detection grating is provided in an optical path between the scale and the light receiver, and
the light receiver detects a component of a second spatial frequency that is lower than the first spatial frequency in the light intensity distribution transmitting through the detection grating.

Assignees

• Canon Kk

Inventors

• Nagura Chihiro

Classifications

• G03F7/70616

  Monitoring the printed patterns · CPC title

• G05B19/4182

  manipulators and conveyor only · CPC title

• G01D5/38

  by diffraction gratings · CPC title

• G05B19/402

  characterised by control arrangements for positioning, e.g. centring a tool relative to a hole in the workpiece, additional detection means to correct position (G05B19/19 takes precedence) · CPC title

• G03F7/70775 Primary

  Position control, e.g. interferometers or encoders for determining the stage position · CPC title